Insulation for refrigerator cars



Mareh 27, 1934.

vH. DoNQvAN INSULATION FO'i REFRIGERATOR CARS Filed De'c. 5, 1931 Inlfen;

Patented Mar. 1934 PATENT OFFICE INSULATION `rolt REFRIGERATOR oAns Henry Donovan, Chicago, Ill., assigner to North American Car Corporation, Chicago, Ill., a corporation of Illinois Application December 5, 1931, Serial No. 579,267

7 Claims.

This invention relates to certain new and useful improvements in insulation for refrigerator cars, and more particularly to an improved insulated car construction particularly adapted for shipping solidified carbon-dioxide.

Solidied carbon-dioxide has an extremely low temperature, approximately 109 below zero Fahrenheit. As is well known, this material passes directly into the gaseous state without passing through an intermediate liquid state. This change from the solid to the gaseous state involves the absorption of considerable quantities of latent heat, and since the material is easily handled and does not produce any objectionable moisture, it is very desirable and useful as a refrigerant. Due to the extremely low temperature of the solid product, it is essential that it be very thoroughly insulated while in storage or during shipment, in order to avoid undueloss through vaporization. The .present invention relates particularly to certain improvements in the construction and insulation of a railway car designed especially for shipping this product.

More specifically the improved car is divided in to a plurality of separated compartments, each having imperforate side, end and bottom walls, and provided with a hatch lopening or openings in the roof of the car through which the compartments may be loaded or unloaded. The invention includes improved means for sealing andl insulating these hatch openings. The invention also includes improved means for rendering the insulating walls of the compartment impervious tothe passage therethrough of air or moisture either from outside or inside the car.

The principal object of this invention is to provide certain improvements in the insulation for -refrigerator cars, such as briey referred to hereinabove and disclosed more in detail in the specifications which follow.

Another object is to provide an improved process for treating the heat-insulating material in refrigerator car walls to render this material impervious to air.

Another object is to provide improved means for rendering the heat-insulatingwalls moistureproof.

Another object is to provide an improved insulated refrigerator car compartment having closed lower and side walls and provided with an upper hatch opening.

Another object is to provide improved means for sealing the hatch opening embodying the use of a chamber containing gaseous carbondioxide.

(Cl. 62-9L5) Another object is to provide an improved refrigerator car for shipping solidied carbondioxde embodying a plurality of separated insulated compartments each provided with an individual upper hatch opening.

Other objects and advantages of this invention will. be more apparent from the following detailed description of certain approvedconstructions embodying the principles of this invention.

In the accompanying drawing: i

Fig. 1 is a transverse vertical section through a refrigerator car showing the construction of the enclosing walls of a refrigerated compartment.

Fig. 2 is a partial longitudinal elevation of the refrigerator car, showing more or less diagrammatically the division into a plurality of com'- partments.

Fig. 3 is a perspective view of a fragment of insulating board, treated according to this invention to render the same impervious to the passage of air therethrough.

Fig. 4 is a View similar to Fig. 3 showing a. modified construction.

,Referring first to Figs. 1 and'2, the body of the refrigerator car is supported on the usual underframe and trucks, and comprises the usual oor l, side walls 2, and roof 3. The side and end layer of insulating material, as hereinafter described in detail, and the car is divided by a plurality of transverse interior partitions of insulating material into a plurality of entirely separated compartments or chambers A, B, C, etc. (see dotted lines in Fig. 2). The side, end and bottom walls of each compartment are perma nently closed and imperforate, thesolidied carbon-dioxide or other material to be shipped bein`g placed in or removed from the compartments through one or more hatch openings 5 in the roof 3, Athere being two such openings for each compartment, in the example here shown, onev at either side of the central portion of the roof. Improved removable closure members and sealing means (hereinafter described in detail) are used for insulating the hatch openings 5.

Due to the extremely low temperature of the solidified carbon-dioxide, there will be a wide temperature difference between the interior of the shipping compartment and the exterior Walls of the car which may be subjected to the direct rays of the sun. It is necessary,'therefore, to provide comparatively Vthick walls of insulating material to prevent the penetration of heat rays from outside the car to the interior load-holding 'it passes toward the cooler interior.

'the insulating Wall may be subjected.

chamber. It is also highly desirable to prevent or minimize the direct infiltration of warm air through the insulated walls. This inltration of air through the walls, not only raises the temperature within the car, but the vapor laden warm air will deposit its moisture within the walls, as

'Ihis deposition of moisture within the walls not' only impairs the efliciency of the insulation, but adds considerable dead weight to the structure. It has been found that the ordinary insulated walls of a refrigerator car will take up approximately a ton of water after about four months service.

According to this invention, a sheet of heat-insulating board which is used as a constituent of the insulated walls, is coated on one side with a layer of initially viscous material which will harden and render the board impervious to the penetration of air or other gases. An example of a material that has been found suitable for this purpose is marine glue,'as used in ship building.

Such a glue is -a waterproof cement,` known examples of which are made of shellac or caout,

chouc mixed with naphtha or oil of turpentine. In the example shown in Fig. 3, 6 is a sheet of insulating board made of. vegetable bre, suitably treated and pressed into form, numerous examples of such materials now being. in commercial use. A rather heavy coating 7 of the marine glue is brushed or otherwise applied to one face of the fibre-board 6, the material adhering to the face of the bre board and apparently penetrating the board to some extent. The glue will harden and form a permanent hard coating which is impervious to the passage of air or other gases throughout the very wide range of temperatures to which It has been found that approximately 125 pounds of this marine glue will provide a proper coating on one thousand square feet of the insulating board.

In the modied construction shown in Fig. 4, a sheet 8 of fabric, preferably a rather heavy tightly woven canvas, such as is used in ship construction, is secured to one face of the fibreboard 6 by means 'of the marine glue. This construction is very effective for preventing air infiltration, but is more expensive, due to the use of the fabric material, although somewhat less glue is required. It has been found, however, that a suiciently heavy coating of the glue alone (as shown in Fig. 3), is sufficient for the purpose of 'preventing this'air infiltration. Other suitable materials, such as paints, varnishes, or fillers,

capable of maintaining their form throughout the wide range of temperatures to which the walls are subjected, may be used to coat the fibre-board, -but the marine glue is the best example of these materials so far used forthis purpose.

Referring now more specifically to the preferred form of wall construction shown in Fig. 1, thesides and oor have the usual outer sheathing 9 of wood or wood and metal. Directly within this sheathing is placed a lining of heavy water-proof paper, indicated at 10. Within this is placed a layer 11 of the coated .nbre-board, such as shown for example in Figs. 3 or 4. The

' interior of the chamber has a wooden lining 12 provided with a water-proofed interior lining 13, preferably marine cloth. This .water-proofed lining prevents moisture from within the compartment from penetrating the insulating walls. While there is no appreciable moisture formed fromv the solidified carbon-dioxide, some moisture will be deposited on the walls when the compartment is opened and some moisture will be taken in with the load when the chamber is stored with material. This moisture can be' wiped away at times when the chamber is unloaded, and since the walls and floor are continuous'and imperforate, no appreciable moisture will penetrate the insulating walls from within.

The intermediate portions of the insulating walls are formed of asuitable number of layers 14 of heat insulating material, such as balsam wool. Additional intermediate layers of insulating fibre-board may be used as indicated at 15. In the example here shown, an inner layer of fibre-board 16 provided with the glue coating is used directly beneath the inner sheathing 12 of the'floor in addition to the outer layer l0 of this treated nbre-board.

At 17 are indicated interior wooden stringers within the floor insulation for reinforcing this structure 'and supporting the load. Since these wooden stringers are relatively ineicient as a heat-insulator, an intermediate layer 15 of the specially treated fibre-board is interposed between the two superposed rows of stringers to minimize the passage of heat upwardly through the stringers.

The upper hatch openings 5 are of suicient size to permit a workman to get into and out of the compartment, and to permit the solidified carbon-dioxide or other load to be passed through the openings. Preferably the opening 5 tapers slightly downwardly, and a lower closure plug 18 is adapted to fit .tightly within the lower portion of the opening, preferably resting on" inwardly projecting shoulders 19 formed on the side walls of the opening. An upper closure or cover member 20 is hinged to the roof structure at 21 so that it may be swung into or out ofthe opening. The closure members 18 and 20 are interiorly insulated in much the same manner as the walls of the car. 'Ihe closure plugs 18 are preferably lined with marine cloth, similar to the lining 13 of the compartment. 'Ihe plug 18 and 'top closure 20 are so proportioned and positioned that a space or chamber 22 will remain between these membersand within the hatch opening 5, and this space is partially filled with'scraps or fragments of the solidified carbon-dioxide. Gaseous carbon-dioxide is a most effective heat insulator, and the dry fragments will partially vaporize and ll the chambers 22 so as to very eiciently isulate these openings. In the same manner such carbon-dioxide gas as forms within the main chamber from the vaporization of the refrigerant therein, will form a gaseous sheathing around the load to effectively supplement the insulating properties of the surrounding walls. The lining 13, whichis not only water but gastight, will prevent the lescape of this carbondioxide gas through the walls.

It will be apparent that the size, proportions, and specific interior construction of the insulated walls could be varied considerably from the example here shown without departing from the principles of this invention. It is desirable that the infiltration of warm airl from without be stopped at substantially its source, and it is therefore desirable proved coated fibre-board closely adjacent the exterior walls of the car. Itis also desirable to provide a water and gas-tight interior lining for to place a layer of the im" the compartment so as to prevent the seepage of ystructure prevent the direct penetration of heat rays, and since no iiuids can penetrate through the walls, the conduction or convection of heat by means of these agents is also prevented.

I claim:

l. A refrigerator cary adapted for shipping solidifled carbon dioxide, the car comprising insulated side walls, floor and roof, and insulated partitions separating the interior of the car into a plurality of` separate compartments, the side walls, floor and partitions being permanently closed and imperforate, there being hatch openings formed in the roof leading to each compartment, and removable insulated means for seal--v ing the' hatch openings.

2. A refrigerator car adapted for shippingsolidified carbon dioxide, the car comprising insulated side walls, floor and roof, and insulated partitions separating the interior of the car into a plurality of separate compartments, the side walls, floor and partitions being permanently closed and imperforate, there being hatch openings formed in the roof leading to each compartment, an inner insulated closure plug for each opening, means for removably supporting' the 'plug within the lower portion of the hatch opening,y and a removable insulated cover for the top of the hatch opening, the plug and cover being spaced apart to form the bottom and top walls of a closed insulating chamber within the hatch opening in which chamber scraps of solidified carbon dioxide are placed to fill the insulating chamber -with carbon dioxide gas.

3. A refrigerator car adapted for shipping solidified carbon dioxide, the car comprising insulated side walls, oor and roof, and insulated partitions separating the interior of the car into a plurality of separate compartments, the side walls, oor and partitions being permanently closed and imperforate, a lining of Water-proof material for the interior of each compartment, there being hatch openings formed in the roof leading to each compartment, and removable insulated means for sealing the hatch openings.

` 4. A refrigerator car adapted for shipping solidiiied carbon dioxide, the carcomprising insulated side walls, floor and roof, and insulated partitions separating the interior of the car into a plurality of separate compartments, the side walls, iioor and partitions being permanently closed and imperforate, there being hatch openings formed in the roof leading to each compartment, an inner insulated closure plug for each opening, means for removably supporting the plug within the lower portion of the hatch-opening, and a hinged insulated cover for the top of theI hatch opening, the plug and cover being spaced apart to form the bottom and top walls "of a closed insulating chamber within the hatch opening in which chamber scraps of solidified rcarbon dioxide are placed to fill the insulating chamber with carbon dioxide gas.

5. In a refrigerator car, a compartment for shipping solidified carbon dioxide, the side walls, oor and roof of the compartment being insulated, and the side walls and iioor being permanently closed and imperforate, there being a hatch opening leading throughthe roof into the compartment, an inner insulated closure plug, means for removably supporting the plug within the lower portion of the hatch opening, and a removable closure for the top of the hatch opening, the closure and plug being spaced apart to form the bottom and top walls of a closed insulating chamber Within the hatch opening in which chamber scraps of solidified carbon dioxide are placed to fill the insulating chamber with carbon dioxide gas.

6. In a refrigerator car, a compartment forming a portion of the car for shipping solidified carbon dioxide, the side walls, floor and roof of the compartment comprising superposed sheets of insulating material, an outer sheet being coated with marine-glue, and the side walls and :door being permanently closed and imperforate and lined with water-proof material, there being a hatch opening leading through the roof of the car into the compartment, and removable insulated means for vsealing the hatch opening.

7. In a refrigerator car, a compartment for shipping'solidied carbon dioxide, the side-walls,

`floor and roof of the compartment comprising 

